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Merged
merged 1 commit into from
Apr 24, 2025
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Extend HIR to track the source and syntax of a lifetime #139945

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11 changes: 8 additions & 3 deletions compiler/rustc_ast_lowering/src/item.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@ use rustc_ast::*;
use rustc_errors::ErrorGuaranteed;
use rustc_hir::def::{DefKind, Res};
use rustc_hir::def_id::{CRATE_DEF_ID, LocalDefId};
use rustc_hir::{self as hir, HirId, IsAnonInPath, PredicateOrigin};
use rustc_hir::{self as hir, HirId, LifetimeSource, PredicateOrigin};
use rustc_index::{IndexSlice, IndexVec};
use rustc_middle::ty::{ResolverAstLowering, TyCtxt};
use rustc_span::edit_distance::find_best_match_for_name;
Expand Down Expand Up @@ -1868,7 +1868,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
}
GenericParamKind::Lifetime => {
let lt_id = self.next_node_id();
let lifetime = self.new_named_lifetime(id, lt_id, ident, IsAnonInPath::No);
let lifetime =
self.new_named_lifetime(id, lt_id, ident, LifetimeSource::Other, ident.into());
hir::WherePredicateKind::RegionPredicate(hir::WhereRegionPredicate {
lifetime,
bounds,
Expand Down Expand Up @@ -1901,7 +1902,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
}),
WherePredicateKind::RegionPredicate(WhereRegionPredicate { lifetime, bounds }) => {
hir::WherePredicateKind::RegionPredicate(hir::WhereRegionPredicate {
lifetime: self.lower_lifetime(lifetime),
lifetime: self.lower_lifetime(
lifetime,
LifetimeSource::Other,
lifetime.ident.into(),
),
bounds: self.lower_param_bounds(
bounds,
ImplTraitContext::Disallowed(ImplTraitPosition::Bound),
Expand Down
121 changes: 73 additions & 48 deletions compiler/rustc_ast_lowering/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -54,8 +54,8 @@ use rustc_errors::{DiagArgFromDisplay, DiagCtxtHandle, StashKey};
use rustc_hir::def::{DefKind, LifetimeRes, Namespace, PartialRes, PerNS, Res};
use rustc_hir::def_id::{CRATE_DEF_ID, LOCAL_CRATE, LocalDefId};
use rustc_hir::{
self as hir, ConstArg, GenericArg, HirId, IsAnonInPath, ItemLocalMap, LangItem, ParamName,
TraitCandidate,
self as hir, ConstArg, GenericArg, HirId, ItemLocalMap, LangItem, LifetimeSource,
LifetimeSyntax, ParamName, TraitCandidate,
};
use rustc_index::{Idx, IndexSlice, IndexVec};
use rustc_macros::extension;
Expand Down Expand Up @@ -1079,7 +1079,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
itctx: ImplTraitContext,
) -> hir::GenericArg<'hir> {
match arg {
ast::GenericArg::Lifetime(lt) => GenericArg::Lifetime(self.lower_lifetime(lt)),
ast::GenericArg::Lifetime(lt) => GenericArg::Lifetime(self.lower_lifetime(
lt,
LifetimeSource::Path { with_angle_brackets: true },
lt.ident.into(),
)),
ast::GenericArg::Type(ty) => {
// We cannot just match on `TyKind::Infer` as `(_)` is represented as
// `TyKind::Paren(TyKind::Infer)` and should also be lowered to `GenericArg::Infer`
Expand Down Expand Up @@ -1198,35 +1202,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
TyKind::Slice(ty) => hir::TyKind::Slice(self.lower_ty(ty, itctx)),
TyKind::Ptr(mt) => hir::TyKind::Ptr(self.lower_mt(mt, itctx)),
TyKind::Ref(region, mt) => {
let region = region.unwrap_or_else(|| {
let id = if let Some(LifetimeRes::ElidedAnchor { start, end }) =
self.resolver.get_lifetime_res(t.id)
{
debug_assert_eq!(start.plus(1), end);
start
} else {
self.next_node_id()
};
let span = self.tcx.sess.source_map().start_point(t.span).shrink_to_hi();
Lifetime { ident: Ident::new(kw::UnderscoreLifetime, span), id }
});
let lifetime = self.lower_lifetime(&region);
let lifetime = self.lower_ty_direct_lifetime(t, *region);
hir::TyKind::Ref(lifetime, self.lower_mt(mt, itctx))
}
TyKind::PinnedRef(region, mt) => {
let region = region.unwrap_or_else(|| {
let id = if let Some(LifetimeRes::ElidedAnchor { start, end }) =
self.resolver.get_lifetime_res(t.id)
{
debug_assert_eq!(start.plus(1), end);
start
} else {
self.next_node_id()
};
let span = self.tcx.sess.source_map().start_point(t.span).shrink_to_hi();
Lifetime { ident: Ident::new(kw::UnderscoreLifetime, span), id }
});
let lifetime = self.lower_lifetime(&region);
let lifetime = self.lower_ty_direct_lifetime(t, *region);
let kind = hir::TyKind::Ref(lifetime, self.lower_mt(mt, itctx));
let span = self.lower_span(t.span);
let arg = hir::Ty { kind, span, hir_id: self.next_id() };
Expand Down Expand Up @@ -1302,7 +1282,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
}
GenericBound::Outlives(lifetime) => {
if lifetime_bound.is_none() {
lifetime_bound = Some(this.lower_lifetime(lifetime));
lifetime_bound = Some(this.lower_lifetime(
lifetime,
LifetimeSource::Other,
lifetime.ident.into(),
));
}
None
}
Expand Down Expand Up @@ -1393,6 +1377,31 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
hir::Ty { kind, span: self.lower_span(t.span), hir_id: self.lower_node_id(t.id) }
}

fn lower_ty_direct_lifetime(
&mut self,
t: &Ty,
region: Option<Lifetime>,
) -> &'hir hir::Lifetime {
let (region, syntax) = match region {
Some(region) => (region, region.ident.into()),

None => {
let id = if let Some(LifetimeRes::ElidedAnchor { start, end }) =
self.resolver.get_lifetime_res(t.id)
{
debug_assert_eq!(start.plus(1), end);
start
} else {
self.next_node_id()
};
let span = self.tcx.sess.source_map().start_point(t.span).shrink_to_hi();
let region = Lifetime { ident: Ident::new(kw::UnderscoreLifetime, span), id };
(region, LifetimeSyntax::Hidden)
}
};
self.lower_lifetime(&region, LifetimeSource::Reference, syntax)
}

/// Lowers a `ReturnPositionOpaqueTy` (`-> impl Trait`) or a `TypeAliasesOpaqueTy` (`type F =
/// impl Trait`): this creates the associated Opaque Type (TAIT) definition and then returns a
/// HIR type that references the TAIT.
Expand Down Expand Up @@ -1474,9 +1483,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
precise_capturing_args: &[PreciseCapturingArg],
) -> &'hir [hir::PreciseCapturingArg<'hir>] {
self.arena.alloc_from_iter(precise_capturing_args.iter().map(|arg| match arg {
PreciseCapturingArg::Lifetime(lt) => {
hir::PreciseCapturingArg::Lifetime(self.lower_lifetime(lt))
}
PreciseCapturingArg::Lifetime(lt) => hir::PreciseCapturingArg::Lifetime(
self.lower_lifetime(lt, LifetimeSource::PreciseCapturing, lt.ident.into()),
),
PreciseCapturingArg::Arg(path, id) => {
let [segment] = path.segments.as_slice() else {
panic!();
Expand Down Expand Up @@ -1739,22 +1748,40 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
) -> hir::GenericBound<'hir> {
match tpb {
GenericBound::Trait(p) => hir::GenericBound::Trait(self.lower_poly_trait_ref(p, itctx)),
GenericBound::Outlives(lifetime) => {
hir::GenericBound::Outlives(self.lower_lifetime(lifetime))
}
GenericBound::Outlives(lifetime) => hir::GenericBound::Outlives(self.lower_lifetime(
lifetime,
LifetimeSource::OutlivesBound,
lifetime.ident.into(),
)),
GenericBound::Use(args, span) => hir::GenericBound::Use(
self.lower_precise_capturing_args(args),
self.lower_span(*span),
),
}
}

fn lower_lifetime(&mut self, l: &Lifetime) -> &'hir hir::Lifetime {
self.new_named_lifetime(l.id, l.id, l.ident, IsAnonInPath::No)
fn lower_lifetime(
&mut self,
l: &Lifetime,
source: LifetimeSource,
syntax: LifetimeSyntax,
) -> &'hir hir::Lifetime {
self.new_named_lifetime(l.id, l.id, l.ident, source, syntax)
}

fn lower_lifetime_anon_in_path(&mut self, id: NodeId, span: Span) -> &'hir hir::Lifetime {
self.new_named_lifetime(id, id, Ident::new(kw::UnderscoreLifetime, span), IsAnonInPath::Yes)
fn lower_lifetime_hidden_in_path(
&mut self,
id: NodeId,
span: Span,
with_angle_brackets: bool,
) -> &'hir hir::Lifetime {
self.new_named_lifetime(
id,
id,
Ident::new(kw::UnderscoreLifetime, span),
LifetimeSource::Path { with_angle_brackets },
LifetimeSyntax::Hidden,
)
}

#[instrument(level = "debug", skip(self))]
Expand All @@ -1763,7 +1790,8 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
id: NodeId,
new_id: NodeId,
ident: Ident,
is_anon_in_path: IsAnonInPath,
source: LifetimeSource,
syntax: LifetimeSyntax,
) -> &'hir hir::Lifetime {
let res = self.resolver.get_lifetime_res(id).unwrap_or(LifetimeRes::Error);
let res = match res {
Expand All @@ -1787,17 +1815,13 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
}
};

#[cfg(debug_assertions)]
if is_anon_in_path == IsAnonInPath::Yes {
debug_assert_eq!(ident.name, kw::UnderscoreLifetime);
}

debug!(?res);
self.arena.alloc(hir::Lifetime::new(
self.lower_node_id(new_id),
self.lower_ident(ident),
res,
is_anon_in_path,
source,
syntax,
))
}

Expand Down Expand Up @@ -2389,7 +2413,8 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
self.next_id(),
Ident::new(kw::UnderscoreLifetime, self.lower_span(span)),
hir::LifetimeKind::ImplicitObjectLifetimeDefault,
IsAnonInPath::No,
LifetimeSource::Other,
LifetimeSyntax::Hidden,
);
debug!("elided_dyn_bound: r={:?}", r);
self.arena.alloc(r)
Expand Down
17 changes: 10 additions & 7 deletions compiler/rustc_ast_lowering/src/path.rs
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Original file line number Diff line number Diff line change
@@ -1,10 +1,9 @@
use std::sync::Arc;

use rustc_ast::{self as ast, *};
use rustc_hir as hir;
use rustc_hir::GenericArg;
use rustc_hir::def::{DefKind, PartialRes, Res};
use rustc_hir::def_id::DefId;
use rustc_hir::{self as hir, GenericArg};
use rustc_middle::{span_bug, ty};
use rustc_session::parse::add_feature_diagnostics;
use rustc_span::{BytePos, DUMMY_SP, DesugaringKind, Ident, Span, Symbol, sym};
Expand Down Expand Up @@ -433,23 +432,27 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {

// Note: these spans are used for diagnostics when they can't be inferred.
// See rustc_resolve::late::lifetimes::LifetimeContext::add_missing_lifetime_specifiers_label
let elided_lifetime_span = if generic_args.span.is_empty() {
let (elided_lifetime_span, with_angle_brackets) = if generic_args.span.is_empty() {
// If there are no brackets, use the identifier span.
// HACK: we use find_ancestor_inside to properly suggest elided spans in paths
// originating from macros, since the segment's span might be from a macro arg.
segment_ident_span.find_ancestor_inside(path_span).unwrap_or(path_span)
(segment_ident_span.find_ancestor_inside(path_span).unwrap_or(path_span), false)
} else if generic_args.is_empty() {
// If there are brackets, but not generic arguments, then use the opening bracket
generic_args.span.with_hi(generic_args.span.lo() + BytePos(1))
(generic_args.span.with_hi(generic_args.span.lo() + BytePos(1)), true)
} else {
// Else use an empty span right after the opening bracket.
generic_args.span.with_lo(generic_args.span.lo() + BytePos(1)).shrink_to_lo()
(generic_args.span.with_lo(generic_args.span.lo() + BytePos(1)).shrink_to_lo(), true)
};

generic_args.args.insert_many(
0,
(start..end).map(|id| {
let l = self.lower_lifetime_anon_in_path(id, elided_lifetime_span);
let l = self.lower_lifetime_hidden_in_path(
id,
elided_lifetime_span,
with_angle_brackets,
);
GenericArg::Lifetime(l)
}),
);
Expand Down
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